Rainwater contains small amounts of dissolved minerals that have been blown into the air by winds. In a way, the distillation process is responsible for rainwater. Rain is produced by water vapor evaporating from the earth and condensing in the sky. It takes more energy to heat cold water to 212 o F than it does to change 212 o F water to steam. When water first reaches boiling it has not begun to turn to steam yet.
More energy is needed to begin turning the boiling liquid water into gaseous water vapor.
The bonds holding water molecules as a liquid are not easily broken. If I remember correctly, it takes about seven times as much energy to turn boiling water into steam as it does to heat water at room temperature to the boiling point. They don't call it the Great SALT Lake for nothing. Water in the Great Salt Lake is about 25-percent salt. In other words, about one-fourth of the weight of the water comes from salt.