Is making skim milk an example of solubility?

It can be argued yes because whole milk is an emulsion of milk and cream. Tiny fat globules are suspended (but not SOLUBLE) in the water solution of the milk solids, etc that make up milk. The fat will separate on standing - the "cream rises". Making low-fat and skim milk is separating out more of the fat globules, which were not dissolved in the milk.