A group of scientists from VU University in Amsterdam know that this was once the case - and could happen again. Using data from seismometers placed on the Moon’s surface during the Apollo missions (in particular “moonquakes” registered by these devices) they found that up to 30 per cent of the moon’s deep mantle is molten rock, lying dormant beneath the surface. 

To determine why this molten rock wasn’t moving up to form volcanoes as on Earth, the scientists artificially reconstructed samples similar to the moon rock samples brought back by the moon landings. Compressing and heating these samples, they found their density, and concluded that titanium-rich molten rock would likely have sunk to the deep mantle of the moon during its formation as it was more dense than the materials around it. 

They hypothesise that in the distant future, this molten rock will cool and the most dense parts will solidify, leaving lighter molten rock to move towards the surface and again form volcanoes.

"Today, the Moon is still cooling down, as are the melts in its interior. In the distant future, the cooler and therefore solidifying melt will change in composition, likely making it less dense than its surroundings. This lighter magma could make its way again up to the surface forming an active volcano on the Moon – what a sight that would be!" said team leader Wim van Westrenen in a press release.

[Gizmodo]