Triffid

...does anyone know what this plant is? Its been in my garden since I moved here 4 years ago but it has never grown as big as it has this year ! Its base is wide and the leaves are quite dark and tropical looking and sort of spiky but wide....and the tops are pineapple shaped with these individual buds forming the overall shape.
If I knew what it was called I could look up how and when to prune it before it takes over...its already destroyed my hostas!