Colligative Properties

Show how the boiling point and freezing point of water are affected by the addition of various solutes.  (a) If you were to dissolve 10 g sodium chloride in 500 g water, what would be the boiling point of the solution? (b) If you were to heat the solution in part (a), and continue heating it as it boiled, what would happen to the temperature over time?  (c) in what way is your answer to part (b) contrary to what occurs regarding constant temperature during phase changes?  Explain the apparent contradiction.