Happens to me all the time when making tea. Dropping the tea bag in and watching the cup sputter and froth is the most exciting part of tea.
My advice more generally: avoid Theraflu. That stuff gives me frenzied, unpleasant dreams.
If you were to put a little bit of sugar in the water before microwaving it, would that prevent the superheating?
Yes. Gives the water bubbles the nucleation sites and whatnot.
It also has the side effect of making the sugar dissolve more easily. 
You can also prevent superheating by not, y’know, microwaving the holy hell out of the water. A minute, maybe a minute-and-a-half, is enough for a mug of water.
The only person I know personally who superheated water for tea and got the whole scary phenomenon was a former roommate of mine, who was generally known for not having the sense God gave a grasshopper and specifically for over-microwaving everything. I once caught her just in time putting a little plate of leftovers (a saucer, really) into the nuker on High for six minutes. Jeebus.
Absolute twaddle.
as soon as the sugar dissolves, which it will at room temperature, it will no longer act a as point of nucleation.
Water microwaved (or heated in a kettle) to boiling will give off most of its Oxygen and other dissolved gasses. When it’s cooled, it could act differently when it freezes, though I’d expect it to just make clearer ice. Certainly not mutant, malformed molecules.
I thought the dissolved sugar still maintains its molecular structure. The molecules are just more spread out. So the sugar molecules - which have a different shape from water molecules, obviously - still creates nucleation sites for the bubbles.
Did I misunderstand that?
My old college (hippie) roommate repeatedly used this same “report” and I didn’t buy it then and I don’t buy it today. This does kind of prove this supposed report is somewhat widespread. Regardless, all a microwave does is make the water molecules vibrate faster, which in turn heat it up. Anything that claims microwaved water makes plants die is going to need to provide some real scientific studies.
In my experience, molecules in solution (even really big ones) don’t provide good nucleation points. Case in point:
One of the things I prepare on a pretty regular basis in lab is an agarose gel – which basically consists of a sort of purified seaweed jelly and various salts. More specifically, the agarose itself is a big polysaccharide, and the salt solution consists of some relatively large ions - tris, EDTA (both of which are about the size of a single sugar molecule) and acetate (smaller, but still bigger than water). To melt the agarose, I microwave the stuff rather vigorously (in clean glassware), and once everything is melted I often end up with superheated solution – giving it a little shake will cause a flurry of boiling. Now, while the agarose is still present as particles of undissolved/unmelted stuff on the bottom of the flask, it provides plenty of nucleation sites (you can watch through the microwave’s window), and I don’t see any superheating. Scratches on older, dinged up glassware also provide nice nucleation points.
For the record: “The Hidden Messages in Water” by Masaru Emoto, is the complete bunk that people have mentioned. As far as I know, they took magnified pictures of water and then chose images fitting their hypotheses
Just put a wooden chopstick in it. You can use the same chopstick over and over.
I only remember it, after all this time, because I was very skeptical when I heard it, I’m sure.
This thread reminded me about it and I thought I’d ask.
Thanks pharman. Your answer, neither dismissive nor rude, was just what I was hoping for.
I knew it didn’t sound right, but it was presented as actual science, at the time I saw it.
Oh, and thanks for the snark who ever gets enough of that?
The alleged harm to plants from microwaved water, along with its refutation:
When was the last time you saw sugar dissolve in a class of water at room temp? Maybe a little bit will, but anyone who has tried to make sweet tea by adding sugar to the tea can tell you that you end up with a LOT of sugar crystals floating in the tea. Maybe, after a long time and a lot of stirring, it will dissolve, but it takes a while.
you can dissolve 4 teaspoons of sugar in a glass without stirring too long, half a minute.
you would be surprised at the amount that could dissolve if length of time stirring wasn’t an issue.
Basically, microwave is the same, but adding liquid and powder is tricky in all cookery.
You will find these distinctions in every cookbook. Sometimes add the powder to the liquid and sometimes the reverse.
My cocoa explains that if you put a tablespoon in the bottom of the cup first then the cocoa won’t stick in a lump to the bottom. But the powder floats, so you should then add the powder and while stirring add the rest of water, so the powder won’t sit on top of the water and be hard to stir in.
Powder floating on top in the microwave might get hotter than the water and burn.
That’s just what I was going to post. An earlier poster had suggested a glass stirrer, like a swizzle stick, but that would not have anywhere near the effectiveness of a nice piece of wood, that has a very rough surface with loads of crevices for nucleation. The disposable chopsticks you get with Chinese take-out are perfect.
That brings up another question: What is the most energy efficient way of heating water to boiling? I have a gas stove, an electric kettle and a microwave, and want to heat water to boiling for a nice pot of tea. Which one should I use?
The microwave has nothing to do with super heating the water. As stated previously it is the water requires imperfections in order to nucleate. Water gets superheated because the surface of the glass/ceramic is to “perfect” to allow it to begin nucleation. Not only can this be observed in a cup/glass, but it was a pretty popular experiment that was performed at my high school. Put a super clean test tube in a stand, apply heat, then A) drop something into it, or B) tap/shake the side of the test tube and watch the entire contents erupt into a cloud of steam… All good fun.
Gaffa: The most efficient method of those would be the microwave. If you want the science behind it look up “heat of fusion” (of water), “enthalpy”, and “specific heat capacity”. Understanding those terms should shed some light onto why it is the most efficient.
a microwave is more efficient than a stove top.
i believe an electric kettle, especially if plastic, would be better than the microwave.
The electric won’t be more efficient because it still relies on a heating filament. It may be faster than the microwave, however it won’t be as energy efficient because there is more energy loss from radiant heat(essentially heating water with a light bulb).