Stolen Dumbledore

Greetings to you all, ladies and gentlemen!
I'm new to this forum, but I'd like to become a regular participant. This topic seems really fascinating to me. Similarities between Tolkien's books and the Harry Potter saga are very interesting, though in my opinion they don't make Ms. Rowling's books less original at all. But before expressing my opinions in more detail I'd like to ask a question. It's a bit off topic, I am afraid, but I've been looking virtually everywhere for an answer without any success and it haunts me.

Warning: my question contains a Harry Potter 6 spoiler!

Originally Posted by VanimaEdhel

I sometimes read some of the things they say, such as:

From here on in, Harry, I may be as woefully wrong as Humphrey Belcher, who believed the time was ripe for a cheese cauldron.

and I think, "Dumbledore's kidding, right?" But Rowling takes such eccentric things - such things only found in a child's dreams - and brings them to life.

What exactly is the sense of the joke? Is the cauldron meant for making cheese, or is it full of cheese, or what?
Thank you in advance!