What is the relationship between volcanoes and plate boundaries?
It is because plate boundaries are constantly moving and when they separate it gives the magma a chance to rise and form a volcano. There is also a possibility that they could crash into each other and the denser plates sink underneath, and when this happens it causes friction, then cracks and the magma rises through those cracks and onto the surface. The random volcanoes that are not on a plate boundary are caused by hot spots. This is why the magma is really hot underneath one part of the mantle and starts to melt it away and pushes it through.