Does anyone know the cause of Kallax furniture (and perhaps more Ikea pieces) making a liquid "wooshing" sound when you move/turn over the furniture?
I purchased two Kallax bookshelves from Ikea (Nov 2015). When I flipped the bookshelves over while moving each of them, they each made a "wooshing" sound as though there was liquid inside of the furniture. Could be unrelated, but I also noticed that the furniture had holes on the top, as though to let the furniture "ventilate" (the holes served no functional or design purpose). I could replicate the sound each time I flipped the bookcase over.
Note, I drove the piece from Ikea to back home and put it together as soon as I got home.