Since she was a young child, she has had a fascination with experimenting with soaps, toothpaste, shampoos, lotions, etc. -- bathroom-type
products. She has put them in her hair, mixed them together in potions, etc. We caught her doing this enough (after a suitable punishment) that I removed all such products from her bathroom and her reach, and only brought them out with a parent present during bath time, brushing teeth, etc.