How about water that doesn’t boil, even over 212F?
A couple of weeks ago I was heating water in a pot on the stove. After a few minutes I went to check on it, and it wasn’t boiling. At all. Not even tiny bubbles on the bottom. I started to reach for it, then BAM. The water exploded all over my kitchen (fortunately not over me), and what little remained in the pot was boiling furiously.
I’ve seen that happen with microwaves, but never on a stovetop.
Cool! Mr Wizard had some great ones himself back in the day. A few of my favorites:
He had a fish tank of water and sprinkled this powder all over the surface (lycopodium?). When he reached into the tank to pull an object out, his bare hand wouldn’t get wet. If I recall correctly it was because the powder prevented the surface tension from breaking.
He had two clear liquids in separate jugs (looked just like water). He mixed them together into a clear jug and seemingly nothing would happen. Then after an exact amount of time had elapsed, the entire thing would turn completely black instantly. Freaky to see as a kid, but I think I’d be just as delighted to see it today.
Dang, I miss Mr Wizard. Do they air reruns anymore?
Check out the Nova episode Hunting the Elements, especially the guy with the Periodic Table table. He has a mechanism to drop sodium into water, causing little explosions as hydrogen & oxygen separate. He also combines sodium with chlorine to create sodium chloride smoke.