Tutorial Problem With Particles?

I’ve tried going through this tutorial several times (I’m using Blender 2.93) but I always end up getting these bubbles coming out of the text and my computer slows down to a crawl - and its a pretty strong machine - although maybe the graphics card needs an upgrade? GeForce GTX 750i)

This is the tutorial:

The effect is supposed to be an explosion modifier - why am I getting bubbles?

Ah ha! I noticed its when I click on “Use Modifier Stack” that I get those bubbles. Is it somehow uses data from a previous particle use? Because in my last work I did use those bubbles from the Particle System? How do you clean all that stuff out?