Lifting a wheel is insufficient roll resistance, namely sway bars that aren't stiff enough, or swaybars that are too stiff at the opposite end of the car. It can also be from suspension not having enough droop for the wheel to remain in contact with the road.
In this pic of my car, you can see what I mean. Rear 24mm Whiteline swaybar on full hard, front is stock GD wrx swaybar. Inner rear is lifting as the rear swaybar is stiff and the front isn't stiff enough. The chassis slop makes up the difference and you lose grip. 80% of the grip is on the outside wheel but the instant that inner wheel comes off you lose 20% of the overall available grip.
The trick is to have well matched swaybars, in my case above reverting the rear back to stock or on a softer setting would probably increase understeer a little but as the bars are more evenly matched the wheels would have all stayed on the ground and overall I would have had more grip. In that particular case, I spun out
