When any boat type or minecart variant interact with cacti or in most cases lava or fire disappear in the special case of the tnt minecart and lava or fire it will ignite 

to recreate have a boat or minecart impact either lava, fire or a cacti and it will wobble and disappear leaving no dropped item.

i have searched using keywords to see if this a duplicate and i have found nothing but it off chance this is i apologize and thank you for taking your time to read this

(i have not attached a image as the bug will not be able to be shown in that form of media)