My cat throws up a foamy whitish clear liquid....?

I started feeding her Wellness chicken formula and 1 boiled chicken dialy. (2 meals a day- morning and night) About every week or so I will watch her eat gr down by our lake and then throw up what I stated above. Is this normal for cats? She does not throw up any food, just the liquid....... She is a bit small for her age because she was the runt of the litter, but the vet told me she was healthy but I could add a chicken in with her normal food for extra protien. I also give her a hairball remedy once a week....... does this sound any bit normal for my baby?