What are some practical applications of freezing point depression, boiling point elevation, and vapor press?
Have you never seen the roads salted in winter?
See this old answer. And this is a clear exploitation of the melting point depression phenomenon.
And at a more practical level for chemists, boiling point elevation, and freezing point depression phenomena can be used to assess the molecularity of a solute, and sometimes an accurate molecular mass.
And as another example, consider ice-cream. Chemists usually use liquid-nitrogen to make ice-cream. You COULD use water-ice doused with common salt to depress the melting point of water LOWER than