Listened to Pots Never Boil?

August 9, 2011 3:43 PM

Why does my pot of water sound like it's boiling, but when I lift the lid nothing's happening yet? What's making all the noise?
posted by Caravantea to Food & Drink (7 answers total)

Is it water trapped against the burner under the pot boiling away as it evaporates?
posted by bq at 3:46 PM on August 9, 2011

Some water is already boiling at the contact surface between water and the heat source, no matter whether that would be the bottom of the pot or the heat-thingy in a water boiler. So steam is forming and makes a racket. Takes a while to heat all the water through to have the entire content boil, though...
posted by Namlit at 3:47 PM on August 9, 2011

It's not the steam forming that makes the racket. The noise comes from bubbles that had started to form at the bottom of the pan, but collapsed either before they detached from the surface or after they detached and escaped to cooler water, forcing the vapor to condense back into water.
posted by lex mercatoria at 4:02 PM on August 9, 2011 [6 favorites]

Those are bubbles churning that are too small to be visible. Air starts coming out of solution as soon as the water starts to heat, as the solubility of gas in water goes as 1 / temperature.
posted by bukvich at 4:28 PM on August 9, 2011

I find that my (clad) pots creak a bit as they heat up. I'm guessing that since aluminum and stainless steel have different thermal expansion coefficients, they're sliding against each other just slightly.
posted by supercres at 4:31 PM on August 9, 2011

Bubble Cavitation.
posted by backseatpilot at 4:58 PM on August 9, 2011 [2 favorites]

I was surprised when I found this happening in my first apartment away from home. I had grown up with a gas stove - this place had electric coil burners. The coil gets hot enough (and the kettle bottom is thin enough to transmit it quickly and unevenly) to boil the water at the bottom of the kettle, but the bubbles of water vapor cool before they rise very high at all, and collapse back into liquid water.

I learned to watch the kettle for steam or listen for the whistle. If it bugs you, you can get a kettle with a thicker bottom or a heat diffuser.
posted by WasabiFlux at 8:48 PM on August 9, 2011