It's an industrial vacuum chamber. It was set up for degassing silicone mold making rubber.
Admittedly I'm not a scientist but ...
In a nutshell what happens is using a high speed mixer.. or in my case... shaker, severely agitates the glycerin introducing very many tiny bubbles making it frothy. Theoretically the heavy agitation helps speed up the combining process of the various ingredients.
Then I put it in a vacuum chamber and the pump pulls out the air.
The tiny bubbles expand and combine making the liquids level rise in the container. When the vacuum gets to around 29.9 hg the liquid "falls" to it's actual level and is bubble free.
Also.. to my understanding, some flavors contain alcohol which may leave a bad taste (why many say letting it breath (evaporate) helps) Well with the vacuum pulling the air through and out of that frothed mix, it seems that it will speed up that process too.
Yeah I'm quite curious... I'll get around to testing soon