PowerShell supports dynamic breakpoints. They trigger when certain requirements are met. Like regular breakpoints, they all require that your script has been saved to a file.
This line will set a breakpoint for script c:\test\script.ps1 that always triggers when the script accesses the variable $Server, read or write:
Set-PSBreakpoint -Script 'c:\test\script.ps1' -Variable Server -Mode ReadWrite
Check out the other examples in PowerShell’s help:
Get-Help -Name Set-PSBreakpoint -Examples