I'm not sure if my experience falls into this category or not.
Begin 2015, my husband was hospitalised with heart problems - the first of what was to be many hospital admissions. The morning after his admission as I was getting up, I had one foot on the floor and was about to stand when all of a sudden his father walked into our bedroom. I looked at him and asked in amazement what he was doing there. Looking exactly the same as I'd last seen him, only younger, without saying anything he smiled at me, walked over to the bed and took my hand, as he placed his hand in mine he simply disintegrated before my eyes. My father-in-law passed away in 1972. When I told my husband what had occurred that morning he simply said "oh that was dad coming to say everything would be alright" and we left it at that. I now know differently, in 2016 my husband was diagnosed with stage four bowel cancer that had metastasized - lungs - bones - liver. He passed away late June 2017 after battling the disease for exactly one year and one day. The visitation was I'm almost certain of it, was to prepare me for what was to come.
A few days after my husband's funeral, I received a notification from his MOB to mine, saying go to messenger that there was a message for me - of course there was nothing there, all in all there have been 8 of these notifications since his passing, the last call being on the 8th of December 2017. Please be aware I am neither psychic or clairvoyant - these experiences have not frightened me in anyway whatsoever but if anything, help a little in my mourning process.