Wait, why did this catch fire?

Someone heats wax in a test tube until it’s boiling. The test tube is then immersed in cold water and the paraffin autoignites? WTH?
Paraffin Wax Autoignition - YouTube

My best guess is that the paraffin vapor was hot enough, but it wasn’t well-enough mixed with the air. Putting it in cold water created sudden turbulence, which mixed the vapor and the air, which then led to the ignition.

Was thinking that the immersion in cold water caused the condensation of one/some paraffin fractions which were inhibiting the ignition of the paraffin vapour.

That was my WAG too: the “correct” stoichiometric ratio was achieved.