This is because stronger intermolecular bonds require more energy to break. As this energy is supplied in the form of heat when boiling, substances with stronger bonds will have a higher boiling point. The order of strength of intermolecular forces is; London dispersion forces < dipole-dipole < Hydrogen bonding
The higher the inter molecular forces, the higher the boiling points. All else being held constant, the stronger the inter molecular forces between atoms or molecules, the higher the boiling points.
