Boiling is the process by which a liquid turns into a vapor when it is heated to it’s boiling point. The change from a liquid phase to a gaseous phase occurs when the vapor pressure of the liquid is equal to the atmospheric pressure exerted on the liquid. Boiling is a physical change and molecules are not chemically altered during the process.
Hope that helped!
<em>Nuclear power releases less radiation into the environment than any other major energy source.</em>