It could potentially shift a bit, you could tile on to an mdf board which is secured in place it wouldn't move and is very stable, go for quite a thick board so there is no flex and make sure you seal everything up very well the last you would want is water ingress in to the board. The other alternative (and probably what I would recommend) would be to go for glass upstands/splashbacks they are extremely heat proof and wouldn't crack over time.