...but it the explanation is in German. ;-)
http://www.wdrmaus.de/sachgeschichte...e.php5?id=2602
As you can see in the video socks can slip into the gap between the washer drum and the gasket. Once they're in there they tend to wrap themselves around the heating element, and with the continuous movement and heat they simply dissolve after some time!
After I learned what happens to our socks I always put them into a mesh wash-bag, I'm tired of buying them by the dozen! I have a whole box full of single-socks hoping to someday meet their partner again! :-D