What exactly was a condensed milk container? If you have seen one in person, it does look rather confusing. Most found today have an underplate, a container with a hole in the bottom and a lid to go on top.
So how does it work? The honest truth is, the condensed milk container's sole purpose was to hide the can of food. Simple as that. In the Victorian times, it was unacceptable to place food on the table in it's original container. Originally the containers were a matching 5 piece set, including a spoon and liner. The spoon and liner are the 2 pieces which are harder to find.
So the hole in the bottom? To push the can out, so you did not have to tip it upside down and spill out the remaining milk. Most condensed milk container's are porcelain but some can be found in metal.