Most national brand colas contain phosphoric acid, which is known for dissolving calcium, among other interesting properties. While this would mean dissolving calcium-based gall stones out of your gall bladder, assuming the phosphoric acid made its way into your gall bladder, it also has an interesting property of leeching calcium out of bones, too.
You'll find info on using phosphoric (and orthophosphoric, and malic) acid(s) in the Liver Flush section of this site.