It is simple to remember the three forms of matter: solid, liquid, and gas. Except studies have discovered a second form of liquid water.

The idea of a second form of liquid water was first proposed three decades ago by researchers at Boston University. The theory suggested that both forms interconvert under high pressure below freezing.

Now, the theory of a liquid-to-liquid transition has been proven using sugar water. Using pure water made detecting the change nearly impossible, leading to researchers in Japan to turn to a sweeter solution.

Using sugar water, the team supercooled the liquid under pressure before decompressing different samples. One of these formed a solid glassy structure which transformed into a liquid when pressure was released.

Sharp differences in density was noted as the pressure changed. This is the liquid to liquid transition, from a high- and low-density liquids.

Due to the use of sugar this still does not constitute ironclad proof of liquid-to-liquid transitions in pure water, but is another piece of evidence in support of its existence.