Couple of things...
1. It's an eisbock - they make a very strong bock beer and then put it in a very cold (-20 C) freezer for a few weeks until it becomes slush and then remove the ice (i.e. water), thereby concentrating the alcohol and flavor. Probably difficult to emulate at home although I think I've heard of people making eisbeer with dry ice.
2. It's no longer the world's strongest beer. That honor now belongs to Brew Dog and their Tactical Nuclear Penguin beer which weighs in at 32% abv. This one uses the same method as the first but starts life as a 10% abv Imperial Stout, so technically I suppose its an eisris.