[quote]Can someone explain exactly how recipes are learned? [/quote]
Eh, not exactly, I can’t.
This is about 50% guesswork, but here goes 😛
You learn craft recipes at semi-random when you improve enough in various crafting relating skills. As you’ve noted, it is not guaranteed that you will be able to use the recipes you get but in general you get ‘earlier’ recipes before ‘later’ ones. There is also a link between the type of skill you use and the recipe you get (not sure if this is a ‘soft’ link or a ‘hard’ link). In your case you should make lots of Sharp Glass shards from sand to boost your glassworking skills.
Except that you shouldn’t, because the Solar Still sucks. Work towards the Stone Still instead. BTW, A desert start is good because you can get lots of Pineapple and Cactus leaves to tide you over until the still produces water.
In theory the method with campfire + glass flask should be good, but you need both Furnace (stone) and Kiln (sandstone) and it is often difficult to get both.