Adding salt to water raises the boiling point of water. This means that the water will take longer to reach its boiling point when salt is added. The boiling point of water is the temperature at which the vapor pressure of the water is equal to the pressure surrounding the water. When salt is added to water, the vapor pressure of the water decreases, which means that the water must be heated to a higher temperature in order to reach its boiling point. The amount by which the boiling point is raised depends on the concentration of salt in the water.