Remember as a kid seeing a 50s B-film with some military personnel finding small rocks that, when taken out of water, burnt through a wooden table... that's all I recall.
This sounds like "Dune Roller" a story by Julian May, which was also made into a story in a radio science fiction series, and into an episode of "Tales of Tomorrow". It has been the answer to several questions here. For example, take a look at this synopsis from another SFF question:
The plot is very much as you describe. It appears that long, long ago a glowing meteor crashed down into Lake Michigan, and lots of little bits and pieces of it apparently were separated by the heat and stresses of reentry and, ever since, have gradually been trying to join together again. It appears that the main globe -- the "Dune Roller" which had gradually become a mere folk tale in that region -- spent most of its time down at the bottom of Lake Michigan, where nobody could see it unless it was attracted by some tiny fragment of itself which was near the lake but couldn't move itself down into the lake to seek the large sphere. Small "amber drops" could self-propel slowly if there wasn't too much of an obstacle in the way, but the big dune roller could move at a very fast pace, even chasing down a motorboat on the surface of the lake. At one point, when a girl named Jeanne discovers that last point the hard way while piloting a boat and wearing an amber drop as a piece of jewelry which her boyfriend (an expert on "dune ecology") gave her, she describes the pursuing sphere as "fifteen feet high." (Which also indicated that the thing was somehow capable of keeping itself up at surface level for lengthy periods instead of being stuck down on the lake bottom if it didn't want to be.)
And it ends as you describe -- the good guys lured it into a trap and blew it to smithereens, but we learn that individual grains will gradually reassemble into larger bits.
Might be "The Monolith Monsters" from 1957, except the rocks get hot and grow when they are exposed to water instead of when they are taken out of water.