retrosublimislushification – n. a law of physics in which air instantly turns into sugary neutral-taste slushy.  It does not pass through the water stage.

The process can only be initiated when a static sign stating “slushy will be ready in 20 minutes” is on an empty slushy machine.  If it has not yet happened, the sign will still read 20 minutes, so you should come back in 20 minutes and check again.  Repeat until it happens, otherwise it doesn’t happen.