When boiling water for pasta I’ve noticed a lot of noise just as the bubbles are starting to form along the bottom of the pot. A fairly loud hissing sound. The hiss decreases about the time the water reaches a rolling boil. I’m pretty sure most of the time it happens there’s no water on the outside of the pot to explain the noise. It sounds like it’s coming more from underneath the pot, near the heating element.
Any ideas on the source of this noise?
Cavitation from small pre-boil bubbles forming and collapsing near the heat source is possibly one source of the “boiling” sound. This is most active just prior to a rolling boil beginning.
Yeah, I thought of that. But the hiss seems pretty high-pitched to be coming through the bottom of the pot.
For the moment, I’m leaning toward very small amounts of water on the heating element or outside of the pot.
I was under the impression that the noise was generated as dissolved gases leave the heated solution (gases are generallyless soluble in hot liquids than cold). You observe that the noise is greatest near the heat source. This is consistent with the idea that dissolved gases are being driven out of the heated water.
Try boiling a pot of pre-boiled (and cooled) water. This will minimize dissolved gases and should eliminate the noise you hear.
Cecil may have commented on this at some point but I can’t find the ref.