Health officials are warning people of an online challenge going around called the "Boiling Water Challenge". 

So far, at least 8 people have gone to the hospital with severe burns.

Here's how it works: people throw boiling water into the air to watch it turn into tiny ice crystals.

The problem is, a gust of wind can blow the water back onto the person scalding them. 

This only works though if temperatures are extremely cold, ike those of the recent polar vortex.