Water

Water is, in fact, a very unique liquid. Water starts out behaving normally. As its temperature drops, water obediently shrinks together-until it reaches 4 °C. Then, amazingly, water reverses course, its volume slowly increasing as it chills. When water finally freezes at 0 °C, it expands dramatically.

Scientist say waters quirky behavior is caused by the shape of its molecule and how it bonds with one another.

Each water molecule is two hydrogen atoms bonded to one oxygen atom ( that's why water is called H2O). Because of how the atoms share electrons, a water molecule is slightly positively charged at the hydrogen atoms, and slightly negatively charged at the oxygen atom. The molecule's charged ends attract the oppositely charged ends of other water molecules.Hence, we can conclude that due to water's special and unique molecules, they would expand when their temperature is 4 degrees C and below.