Re: Grímsvötn volcano
I think this is the paper you want:
Maﬁc intrusions triggering eruptions in Iceland by O. Sigmarsson
Similar triggers have been proposed for the Soufriere Hills eruption on Montserrat which seems to have had a relatively cool, mostly crystalline magma chamber that then received an injection of very hot mafic material. That created local melting, parts of the crystal slush in the chamber largely melted, became mobile and began to move up towards the surface.
Injections of magma are well-known to trigger eruptions - new material can simply overpressurise the magma chamber, the heat can cause a greater degree of melting and more mobile magma, it can cause gases to exsolve from the magma, or it can introduce new gases into the chamber.