I’ve made yogurt a few hundred times, mostly with a yogurt maker (picture below). The usual recipe is 1 quart milk, 1/4 teaspoon whey (from previous batch), incubate 24 hours. Yesterday, after incubation finished, I opened the machine to find this:
The milk (now yogurt) had squeezed together to form a perfectly round disc a few inches thick. It had squeezed out all the whey. The only unusual feature of this batch — besides the fact that it is getting warm and relatively humid here in Beijing — is that I used maybe 10% less milk than usual. This difference means the pulling inward force was less resisted by sticking to the sides, so this outcome indeed was more likely than usual.
This is my yogurt maker.
I bought it because it came with a glass bowl. Most yogurt makers have only a plastic bowl. You simply pour the milk in the glass bowl, add the starter (whey), add hot (boiling) water around the glass bowl, and wait a day — infinitely easier than the insanely complicated yogurt recipes I find on the Web. And I am beginning to think the hot water is unnecessary.