If we add impurities to a solution boiling point of the solution increases. This happens because the presence of impurities decreases the number of water molecules available to be vaporized during boiling. Once this took place, it takes a greater amount of heat to make the same amount of impure solution to vaporize as it would take to make a pure solution to vaporize, thus there would be raise in the solution's overall boiling point. It is important to realize however, that impurities do not always increase boiling point, and, in certain rarer cases, can actually cause boiling point to decrease. With this in mind, it is important to know exactly what impurities are being added to a solution in order to determine the final effect the impurities will have on boiling point.