Kitchen Tiles Pushing Out - Possible Leak?

[mattdragon2]

In my kitchen, the tiles near the sink started to push out and no longer align. A couple of them have fallen off.

What could cause this to happen?

It only appears to be the tiles where my sink/window is. No other tiles have pushed out.

If I place the tile against where it was meant to be, there is now a gap too, like somehow the wall has expanded.

I have took a picture. As you can see there are now gaps between the tiles and a couple have fallen off.

[proptech]

Hi mattdragon2

I've come across this a few times before. I think you will find the wall has been added to in order to provide the sill hight behind the sink. This has probably been done with unsuitable materials, and together with a degree of damp, has expanded, lifting it from the original brickwork. No doubt, if you tap the surface it will sound hollow.