1. Reach boiling point: At standard atmospheric pressure, the boiling point of water is 100 degree. Only when the water temperature reaches or exceeds 100 degrees can water boil.

2. Constantly absorbing heat: When the temperature of water reaches the boiling point, it is necessary to continuously obtain heat from the outside. This is because boiling is the vaporization of liquid, which requires energy, and this energy is obtained by endothermic.

3. Boiling refers to the phenomenon that when the liquid is heated above the saturation temperature, it will vaporize violently both inside and on the surface of the liquid. Different liquids have different boiling points, even the same liquid, the boiling point will change with the change of external atmospheric pressure.