Shulkers dont really like to have the new Shulker boxes above them. The attached picture is not the shulker on the box, the sulker is under the box. when it opens it glitches out on top of the box.

step1: place shulker box above the ground
step2: place shulker under the box
step3: wait for the shulker to open
step4: watch the spasms!