They are probably "Messenger Service" popups created by having the Messenger service running on your PC. Disable the service and all should be okay. Post your OS if you need more instructions.
OnePlus 5T review: Hands-on
Illustrator Andrés Lozano on his improv line work, brazen use of colours & hand sketching
iPhone X review
Comment envoyer gratuitement des gros fichiers ?