Concatenating rows into a single cell

Is there a way to dynamically concatenate rows into a single cell using VBA code?

I have a sample where the column highlighted in yellow would be the desired outcome.

Or try:

PHP Code: 

Public Sub MyConcat()
Dim lastRow As Long
Dim i As Long
Dim temp As String
lastRow = Range("B" & Rows.Count).End(xlUp).Row
For i = lastRow To 2 Step -1
    temp = Range("B" & i).Value & temp
    If Range("A" & i).Value <> "" Then
        Range("C" & i).Value = temp
        temp = ""
    End If
Next i
End Sub