The temperature of a liquid remains constant during boiling. This is because the energy added to the liquid is used to change the liquid into a gas, not to increase the temperature of the liquid.

For example, the boiling point of water at sea level is 100 degrees Celsius (212 degrees Fahrenheit). If you heat water above 100 degrees Celsius, it will not get any hotter. Instead, the water will start to boil, and the liquid water will turn into water vapor.

The same principle applies to all liquids. The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the pressure exerted on the liquid by its surroundings. When the vapor pressure of the liquid equals the pressure exerted on the liquid, the liquid will boil.