A vision of Mom

[Quora]

I am not religious and have never thought much about the spiritual/supernatural aspect of death. However, when my Mom died this July, something happened that I can't really explain. I am not looking for a religious explanation, just curious if anyone else experienced something similar and what you think it was? Here's what happened.

There are four children in our family, me being the youngest. I moved to another country (and continent) 3 years ago and haven't seen my Mom in person since then but we were close and kept in touch. This summer, she died of cancer. We haven't talked much in the past 6 months because she was always in pain but we texted. During the last two weeks of her life, I called her a couple of times in the hospital. My siblings and I knew that the situation was bad but we thought that, just like last time, she'd undergo the treatment and everything would be fine. I also have a baby so, while worried about Mom's health, I was busy with the baby and didn't even think of the possibility of her death.

Then one night I went to bed and was thinking the usual "before bed" thoughts - was happened during the day, plans for tomorrow, etc. All of a sudden, in the midst of these mundane thoughts I had this vision, a clear picture in my head, as if I was watching a movie: as if I was looking out of the window of my childhood home and saw my Mom (and I think it was Dad next to her but I couldn't really see him clearly, I was looking at my Mom who was looking me straight in the eye. She looked young, the way she looked in black and white photographs back when she was in her 20s (she was 63 when she died). She had a look on her face which I can describe as solemn and a bit frightened/worried/confused. She looked at me and just like that, the vision was gone.

I felt very uncomfortable right after because it came out of nowhere and scared me but I just distracted myself with good thoughts and fell asleep just to be awaken a couple of hours later by a phonecall with the news... When I talked to my brother who was with her when it happened, he confirmed that she died exactly when I had this vision (it was morning where they live).

Now, my brother who's the oldest of us also felt it that night. He was asleep on the second floor (Mom was on the first) when he has a nightmare: as if Mom's voice said "I died". He woke up and went to check on her. She was still alive but died within an hour as he sat next to her and said his goodbyes, finally realizing that she, indeed, was dying.

Our two other siblings - two sisters - didn't feel anything out of the ordinary.

Mom also told me that she woke up feeling bad in the middle of the night exactly when her mother died, although she also was a thousand miles away.

I keep thinking about what happened that night. It just fascinates me and I keep trying to find information about cases like that. Why did it happen? Why didn't it happen when my father whom I loved so much died 4 years ago? Why did it happen to my brother and I but not our sisters?

I'm grateful that it happened, it felt like she said goodbye to me. But I'm also curious about the nature of it. Especially, whether there is any scientific explanation for it.