Sea water is impure water,so adding salt increases the boiling point of water this is because salt is a non-volatile solute which is responsible for boiling point elevation.
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid and the surrounding pressure are equal.
The original boiling point of water is 100°C. After the addition of 58 grams of salt, the boiling point increases by one half of the degree Celsius