Did it look anything like these?
I lost a female boa two or three months ago to what I believe was kidney failure. She passed urates like that almost daily for a couple of weeks. Never big pees just a lot of them. I asked a couple people up here and they mentioned kidney problems so I asked a three large boid breeders in the states who also mentioned her kidneys were not working properly. Now my girl was severely overweight but the last few days she just stretched out all limp and never had much muscle tone.