Most of the time if something isn't immune to silence you can interrupt most magical- or voice-based moves.

As examples, the magic spells cast by Succubi and other demon enemies (Void Fire II, Void Thunder III, Mind Melt, etc) can be interrupted with a Silencing move.

Silence will also interrupt Siren's Lunatic Voice and Chimera's Ram's Voice and Dragon's Voice.

There is the odd one like ADS's High Voltage since it is a machine but those are rare.

Stun will interrupt anything with a cast time as long as the boss isn't immune to stun, at least what I have seen, but it also has a very long immunity time if you stun too much. Most bosses have an outright immunity to it as well.