Why, why, why

Oh the ingenuity of a 5 year old. Tonight I has just bathed the twins and taken them to their room when Eli entered the bathroom to go potty. I should of been observant enough to notice he had brought his sonic slushy with him. So I got the twins dressed and ready for bed, but need their toothbrushes which were in the bathroom. I go to the door and Eli is just coming out and shuts the door rather quickly behind him (not a good sign these days). I ask him what is wrong and he tells me nothing but won't let me open the door (hmmmm something is not right). Being bigger and stronger than him I open the door and all over the bathroom floor is water and bits of strawberry (from his slushy). In the middle of it is his brand new large bottle of blue bubbles, open with bits of strawberry on it as well. I quickly deduced that he tried to mix the two (slushy and bubbles) made a mess and tried to clean it up with my hand towel soaked in water. Oh the mess he made. When I asked him Why??? He simply said "I wanted to see what it would do". He did try to clean it up...but Why, why, why?