* Ionic Bonding vs. Hydrogen Bonding: Sodium chloride is an ionic compound, meaning it forms strong electrostatic interactions between positively charged sodium ions (Na+) and negatively charged chloride ions (Cl-). These ionic bonds are very strong and require a lot of energy to break, leading to a high boiling point.

* Urea: Urea is a covalent compound. It forms hydrogen bonds, which are weaker than ionic bonds. While hydrogen bonds contribute to urea's relatively high melting point, they aren't as strong as ionic bonds.

In summary: The stronger the intermolecular forces holding a substance together, the more energy is needed to overcome them and cause the substance to boil. Sodium chloride's ionic bonds are much stronger than urea's hydrogen bonds, resulting in a significantly higher boiling point.