Non-explosive volcanoes will have low concentrations of gas in the magma.
Cinder cone volcanoes produce small explosive eruptions.
Eruptions at shield volcanoes are almost always non-explosive.
Magma and lava also crust?
The phrase "explode slowly" is an oxymoron. Composite volcanoes, regardless of whether they are island volcanoes or mainland volcanoes, will produce both explosive and non-explosive eruptions.
Strato and Cinder-cone volcanos but cinder cones can have non explosive too but not strato
Shield volcanoes are generally not explosive. However, soemtimes a type of explosive event called a phreatic eruption can occur if the magma comes in contact with water.
Large explosive eruptions are generally characteristic of stratovolcanoes.
A composite volcano is the most explosive type of volcano there is. Mt. St. Helens and Mt.Vesuvious in Pompeii are both examples of composite volcanoes, and look at the damage they did. a composite volcano usually has pyroclastic flows to accompany the traditional lava and ash.
Explosive volcanoes are most common at subduction zones.
Rhyolite caldera complexes are the most explosive volcanoes, although other types of volcanoes can also erupt.
Volcanoes in Japan have explosive eruptions because there is a a magma chamber that has not completely move along the mantle yet so when it erupts it has explosive eruptions.