Liquids do too cook off!
I count on it to make my apple butter! I fill the crock pot with home made, sugar free apple sauce. Add a couple of tablespoons of apple cider vinegar. Add 1 1/2 tablespoon Apple Pie Spice, and cook on low overnight. I give it a stir every time I get up to go potty.
In the morning, it has reduced by half, and is wonderful, sugar free apple butter.
If you have never canned before, but are interested in learning how to preserve this wonderful stuff, shoot me a PM, and I’ll tell you what you need to know, and also give you some links that I rely on for good canning information.
Just made a batch of that myself last night! Full apple/sugar recipe.