Creeper exploding outside building without seeing me

I’ve experienced creepers detonating outside of any house / buildings without seeing me through windows or no windows at all. I would just hear something hissing outside my house or other buildings then would hear an explosion afterwards realizing a creeper just detonated outside near where I am inside. This would of course damage the walls of the building and the ground outside. As of this writing it happened at least 3 times already.