Bromelain is a very strong binder and it is a good idea to be sure to drink lots of water when using it. Taking a lot of supplements in general, and especially taking lots of minerals, can lead to kidney stones and I am sure that it would be even more likely for that to happen if you were to take a lot of bromelain without lots of water.
Keeping the kidneys regularly cleansed and de-toxed is a good idea. Also, fasting for a day on nothing but watermelon will dissolve kidney stones and is a good kidney and colon cleanse as well. I do so at least once a month and usually twice.
Fasting for one day each week is, in my opinion, a great way to keep the body cleansed and to obtain and maintain optimum weight and health. When I fast, I alternate between watermelon, grapes and grapeseeds, juiced vegetables and fruits, and water. I also take regular breaks for a day to a week or longer from various supplements to avoid buildups and built up tolerance.