I used to have a Northcraft 5.8 that used to do it only at full bung. it was frightening. The hull would suddenly flip to the left, then back to the right. You had to be a wee bit sharpish on the throttle to kil it, In the end, the dealer fitted a wedge to the transom, so I could trim the motor down further, which cured it. It only happened in minor to flat seas, since it was these conditions that would get enough of the hull out of the water. The other thing I used to do to help prevent it was use water ballast in the bow, get about 4 plastic 25L drums full of seawater. Wasn't pretty, bit it worked. The thing about it was, whenever it happened, it was your crew that got the willies, not nice.