Why do we hear noise before boiling?

Before the water boils, we hear a noise. From below, the layers of water are warmed up more, and the higher, the colder the water. Until the water warms up throughout the volume, this noise does not disappear. A gas bubble (air dissolved in water) grows in volume, and the upper layers of cool water act on it, therefore, when the bubble rises, its so-called “collapse” begins. If there were few such bubbles, then the noise would not have been heard, and since there are millions of them, the noise is significant. This process is called cavitation in physics.