English: Boiling is a physical process of intense vaporization that occurs in a liquid, both on its free surface and inside it. In this case, bubbles containing air and saturated steam are formed on the walls of the vessel. During slow boiling bubbles filled with steam appear on the walls or at the bottom of the vessel. Due to the intense evaporation of the liquid into the bubbles they grow, float, and the steam is released into the vapor phase above the liquid.