Not to say that such "supernatural" (or something that is just not understood) acts definitely do not exist, but my rational mind thought about water and Sodium metal.
In its pure state, Sodium is a soft metal. When in contact with water, it would burn and react violently (with hissing and corrosion) to form Sodium hydroxide. I wonder if the ground could have been seeded with Sodium metal or some other similar metal
I have also heard about the case where a bomoh would tell his troubled client that he would need to look in a certain place for a certain keris which would rid him of his troubles. And when the client looked, sure enough, there was a keris buried in the vicinity.
But I'd like to see these things for myself someday.