I just had a strange experience. I moved and my 1/4 oz of menthol crystals was inside a little plastic bag with a press seal top. I think it was sealed or close to it. The bag was inside a closed plastic tackle box, again not quite waterproof, but resistant. The tackle box was inside a moving box with other items. The moving box was in transit for about a week coming across America.
When I went to look for my menthol, it was gone! The bag was still closed, the inside of the tackle box was smeared with the unusable remains of the menthol. It seems unlikely that water could have gotten in; nothing else looked wet, or like it had been wet.
Could it have melted from being left in a hot place somewhere?