I've noticed that when water boils, it makes a lot of noise. After the water reaches boiling point, even though the water is still ""rolling", the water quiets down. What is all the noise about and why does it go away?

  • $\begingroup$ It makes several different kinds of noise which peak at different moments. The whole thing is complicated and not necessarily well understood. $\endgroup$ Dec 20, 2019 at 14:54
  • 1
    $\begingroup$ One noise might be due to all the gases that were dissolved in the water (mostly carbon dioxide, some oxygen) that are driven out before it boils. $\endgroup$
    – Karsten
    Dec 20, 2019 at 14:55
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    $\begingroup$ See also physics.stackexchange.com/questions/375243/… and physics.stackexchange.com/questions/28069/… $\endgroup$
    – user7951
    Dec 20, 2019 at 15:04

1 Answer 1


Oh, you've come to the right place. Many years ago I asked this question as a kid on a TV write-in programme called Don't Ask Me. The TV people invited me on the show and built a series of demonstrations to explain.

The first thing that happens when you warm up a cold pot of water is that the pan bottom gets to boiling temperature. The water starts to boil. Liquids boil when their vapour pressure equals atmospheric pressure. Otherwise bubbles could not form in the the liquid. So, the pan bottom gets hot, bubbles form, but then they move up into cooler water and implode as the vapour pressure drops. This makes a sharp snapping sound. Lots and lots of these imploding bubbles make a roaring sound.

As convection currents then start to mix up the water, it becomes more uniform in temperature, and the bubbles actually rise to the top of the liquid and burst. The implosions stop and you get the softer bubbling sound.

Hope this answers your question!


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