Evolving is a survival mechanism of your body to adjust to your skills, which also means it uses a lot of your energy. Evolving while hunting for monsters isn’t ideal, truth be told.
Evolving a lot will change your appearance more and more, though while it comes with its perks, it drags its consequences right behind. For example, you evolved for quite a while now, reaching for the stars – becoming the very best. Then your next evolutions turns you into a ghost, able to levitate above the ground and reach through walls. But now you have lost the ability to speak, since you no longer have vocal chords.
There is no limit to evolving, only common sense.