Make glass melt?

So, most glasses are made by melting sand, right? I was talking with a friend when he mentioned something about some people sprinkling some stuff on this glass and the glass melts. I just said at the time ‘really?’ and i believe he said yeah. I didn’t bother then to actually think about it so here I am now wondering if it’s true. Is there an element/chemical or something that can make some (any at all?) type of glass melt? (Not because it’s hot or anything because as I mentioned, it was spread/sprinkled/just simply put on by some people on the glass and he didn’t mention any precautions such as gloves or anything as to using it and if there is something like that that can melt glass and isn’t exactly hot but you need to use precautions, please mention)
Or was it possibly a hoax that he maybe saw on tv or a lie?
AHA! Dissolve! I think that was the actual word that he used. Sorry, melting was probably the wrong word. I couldn’t think of it at that time.