A blast from the past
Definition 1 of 1
Pro Tip 1/3Nostalgic Feelings
The phrase often conveys a sense of nostalgia and can bring back memories filled with emotions. 
Hearing that '90s song was a blast from the past, it reminded me of my childhood summers.
Pro Tip 2/3Positive Surprise
It's usually used to express a pleasant and unexpected reminder of the past. 
The arcade had all the old games – it was a real blast from the past.
Pro Tip 3/3Casual Usage
Use this phrase in casual conversations, as it's informal and friendly. 
Running into my first grade teacher at the mall was such a blast from the past!