Snapping to vertex while scaling I want to snap the outer circle to the inner.

For that i turned on snapping to vertex, selected the scale affect, selected the outer circle and try to scale it down until dimensions of inner circle. But when cursor snaps to one of inner circle's vertices, the outer circles's dimensions jump to infinity, i guess. Like on the image:

Why is this happening?
Switch Pivot Point from Individual Origins to Median Point, don't ask me why in that case it made the scale and snap bug though.