The first thing she expelled (the whitish thing) was a urate, part of their urinary process. Then the liquid pee, then the brown stuff which was her feces. The big snakes can really put out some waste product so that's not at all unusual. If you saw the size of what my own female BP, Ardra, passes as far as urates and feces you'd probably faint LOL. They are the biggest things I've ever seen any BP pass but for her, that's just normal.