Does baking soda and citric acid form a precipitate?

When you mix baking soda and vinegar it becomes like a volcanoe...Just like a bubbly sorta type thing. If your trying it at home make sure your doing it over the sink that way it doesnt become a mess. It also helps me and my Allergies! I have hives(sorta like chicken pox) and I rub it on them and it stops the itch.