When a liquid changes form into a gas, the process is called vaporization. You can watch vaporization when you boil a pot of water.
Vaporization happens in two ways: evaporation and boiling. Evaporation occurs when sunlight shines on water until it changes to vapor and rises into the air. Boiling is the rapid vaporization of a liquid—the steam that comes out of a boiling kettle is actually visible water vapor. Vaporization can be traced back to the Latin vaporem. "a warm exhalation" or "steam."