Here's why:

* Intermolecular Forces: The strength of the attractive forces between molecules (like hydrogen bonding, dipole-dipole interactions, and London dispersion forces) plays a major role in determining boiling point. Stronger forces require more energy to break apart, resulting in higher boiling points.

* Molecular Size and Shape: Larger molecules with more surface area have stronger London dispersion forces, leading to higher boiling points.

* Pressure: Boiling point is also affected by the pressure surrounding the liquid. Lower pressure means a lower boiling point.

Examples:

* Water (H₂O) boils at 100°C (212°F) at standard atmospheric pressure.

* Ethanol (C₂H₅OH) boils at 78.37°C (173°F) at standard atmospheric pressure.

* Mercury (Hg) boils at 356.73°C (674.11°F) at standard atmospheric pressure.

As you can see, the boiling points of these common liquids are quite different due to variations in their molecular structure and intermolecular forces.