Here's why:

* Intermolecular Forces: Boiling point is primarily determined by the strength of intermolecular forces between molecules.

* CF4: CF4 is a nonpolar molecule due to its symmetrical tetrahedral shape. It only exhibits weak London dispersion forces (van der Waals forces).

* CHF3: CHF3 is a polar molecule due to the electronegativity difference between carbon, hydrogen, and fluorine. This creates a dipole moment, allowing for stronger dipole-dipole interactions in addition to London dispersion forces.

* Molecular Size: While both molecules have similar molecular weights, the dipole-dipole interactions in CHF3 make it slightly "stickier" to its neighbors, requiring more energy to break the intermolecular bonds and transition to the gas phase.

Therefore, CHF3 has stronger intermolecular forces and a higher boiling point than CF4.