It doesn’t really answer your question I suppose but: bile acids are related to water homeostasis somehow (for example the kidneys must retain more water when there are bile acids in the blood). I also think it could be the elevated vasopressin (an antidiuretic hormone) that increases the production of bile.
As your problem doesn’t happen to everyone that dry fast, I believe it might be associated with liver or gallblader issues like stones, that could impair the bile flux in the gut.