Boiling point elevation and freezing point depression both arise because added solute changes:

1. The colligative properties share one underlying cause. 2. Vapor pressure lowering is itself listed among the colligative properties. 3. The boiling point is where vapor pressure equals ambient atmospheric pressure. 4. Lowering vapor pressure therefore raises the temperature needed to boil. 5. The same lowering explains why solutions freeze at lower temperatures than pure liquids. _Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 11 'Solutions and Colloids', sections 11.1-11.5_