Ammonia is a colorless gas. The stuff you buy in the supermarket is amonia gas dissolved in water. Usually with soap in it. Ammonia gas is unpleasant and toxic and indeed is very volatile.

I hadn't heard about using liquid dishwashing detergent (stuff like Dawn) to remove oil from stocks but it is a very good oil solvent. I use a lot of it to clean metal parts. It works well as a pre-wash spot treatment if I get oil on my trousers or shirt.