The unusual properties of water are due mainly due to its capacity for hydrogen bonding.
Step-by-step explanation:
Liquids have high boiling point because the molecular weight is high and the capacity of hydrogen bonding is also high. In water the hydrogen atom is positive charged in partial and the oxygen is negative charged in partial. There is not only an existence of a covalent bond between oxygen and hydrogen atoms in water, but the hydrogen atoms are attracted towards the oxygen atoms that are present to its nearby locations.
This property of attraction plays an important role in hydrogen bonding. This bonding is the reason for the collective energy liquid water in ground state to be lower than single gaseous molecules energy in the ground state .