Replacing chipboard on polystyrene flooring

[Cauliflower]

I have a crumby situation - my flat has a kitchenette - ie the kitchen and lounge are one room. The lounge area is carpeted and that meets a strip of vinyl tiled floor which is the length of the kitchen area (which is essentially one side of the rectangle that includes the lounge area). Here's a crumby diagram:

EDIT - I tried to create a crumby diagram but the crumby webpage removed all the formatting so it was even more crumby. So I'll describe it - one large square(ish) room, one side of the room is kitchen and this has a long straight stretch of flooring which butts up to the carpet (which covers the rest of the lounge floor). The kitchen strip of floor is the issue.

So a section of the kitchen strip of floor has become uneven and swollen after years of mini floods and general moisture, and the fact that the floor is chipboard has just made it worse. Who the hell decided chipboard was ok to lay as flooring?!!! Anyway the problem is that I live there, there's no option to take up the whole floor and do a proper job on this. Essentially I want to replace the stretch of kitchen floor, just that visible strip. I can't (won't!) take the kitchen base units out, so I'm looking for a bodge.

But the real issue is that the current floor is vinyl on top of chipboard on top of polystyrene on top of concrete. So nothing to anchor onto.

If I could replace the vinyl, polystyrene and chipboard in that stretch of floor with something solid (and water resistant) that it would be possible to tile on top of (porcelain tiles) then that would be the dream.

I don't see a nice solution... but I'm praying someone can at least give me hope!

 

[Doggit]

If you imagine that a laminate floor is essentially what you've got there, then you'll see that it's not that much of a bad job, but they should have used water resistant chipboard in a kitchen. If the concrete floor is level, then you could prime it with an acrylic primer, fix XPS insulation boards with a flexible tile adhesive, and then use the same adhesive to fix the tiles on top of the insulation. Wickes currently do Mapei flexible adhesive at 3 bags for £40, and the setcrete primer as well, and you can get the insulation boards on eBay.