It seems to me that there are at least two factors here. De-gassing takes place at relatively low temperatures (singing kettle due to many small bubbles) and actual boiling will happen at around 100C. The rate of boiling, after 100C, will depend on the power supplied and the noise will depend on the specific surface and even details of thermal contact between element and water. 'Bumping' is the descriptive term for what you can get under some conditions. Also, the size of a typical kettle can give resonances to the sound inside it and sound louder for some kettles than othersHornbein said:To make coffee I pour a cup of water into the tea kettle and boil that. In this case the boiling doesn't quiet down, instead it gets louder.
The sound produced when water boils is primarily due to the formation and collapse of bubbles. As water heats up, bubbles of steam form at the bottom of the pot and rise to the surface. These bubbles collapse when they reach cooler water, creating noise. Additionally, the movement of water and bubbles contributes to the overall sound.
The sound changes as water gets hotter because the size, frequency, and behavior of the bubbles change. Initially, small bubbles form and collapse quickly, making a higher-pitched sound. As the water temperature increases, larger bubbles form and rise more rapidly, creating a lower-pitched, more consistent sound until it reaches a rolling boil.
Yes, the type of pot can affect the sound of boiling water. Factors such as the material of the pot, its thickness, and shape can influence how sound waves are produced and transmitted. For instance, a thin metal pot may produce a sharper, louder sound compared to a thick, heavy-bottomed pot which might muffle the sound.
The sound of boiling water can be a useful indicator, but it is not always precise. While the change in sound can signal that water is reaching a boil, it is better to visually confirm that the water is at a rolling boil, especially for tasks that require precise temperatures, such as cooking pasta or sterilizing equipment.
Boiling water sounds louder just before it starts to boil vigorously because of the increased activity of bubble formation and collapse. As the water temperature approaches its boiling point, bubbles form more rapidly and in greater numbers. The collapse of these bubbles creates more noise, making the sound louder until it reaches a steady rolling boil.