Overheating is Common issue with most of Smartphone but getting burned up is Quite shocking and rare . This is what apparently happened with a Galaxy S4 user in UAE who bought her device in May. The user saw the Galaxy S4 burning after she had it for charging overnight.The S4 get burned from its Charging point and Flip Cover also cached some fire as u see in the picture.
Samsung Gulf agreed to exchange it for a new Galaxy S4 and a flip cover. and said -
We have gotten hold of the product in question, and will be conducting a thorough examination to determine the exact cause of this incident. We would like to assure our customers that we have always employed strict quality control and safety standards to ensure a safe and pleasant user experience.