You don't see anything because gas is invisible. Water in the liquid state may change to water in the gaseous state. Water evaporates to turn into a gas. Gases are colorless and odorless. You cannot see gas ,but sometimes you can hear it and smell it.
Water can evaporate or disappear with the help of heat.
Changes in temperature can increase the rate or how long it takes water to evaporate . Evaporate means to disappear. Water can evaporate from soil. It evaporates off wet clothes hanging on a clothesline. Plants release water vapor into the air.