How do I clean this piece?

I have this cute little bubbler that I’ve named José. I love this piece and i try to clean it often but i never feel like its all the way clean! I cant scrape all areas of the inside so i know there is build up. For quick washes i just use very hot water or some alcohol and salt. I have yet to try one of the special soaps. Can i just boil the whole thing or would that risk breaking the piece?