Got any domestic mysteries?

Domestic mysteries: things that just seem to be unsolvable.

Example: You put 3 pair of socks into the washer and only 2½ pair come out of the dryer. What happened to the other sock?

I had one recently that baffled me. We opened a new box of Bounce dryer sheets. The box went down at a normal rate with using 1 sheet per dryer load. Until the box was almost empty. Then it stayed at that level for several months, never running out. I was amazed.

It could be any domestic chore: laundry, cleaning, cooking, yard work, etc. And if you have any hypotheses about the cause of your mystery, let us know.

Humor is, of course, welcome.