no matter what i put and how much i put into the cauldron. doesnt look like boiling and pressing E doesnt do anything. i tried some of the combinations of others mentioned in a thread and tried using different ingredients that increase the same body part
edit: just as i wrote this i managed to get bubbles to appear the first time. its really confusing though, its not clear which and how many of each you have to put in the cauldron
oh btw, found out that the chest in your house cleans all contents after save and loading back into the game