Unknown lines(fronts) when running SDS-PAGE

[xzeta]

Hi, I recently start doing SDS-PAGE and western blot. While protocols are available, occasionally I face some strange things.

Firstly, although I have followed the protocol to prepare both resolving and stacking gels, the quality of the stacking gel is very poor. While I suspect the concentration of APS is not right, but I want to ask if it is possible to increase the amount of APS added to the gel?

Another thing, which is more serious than the stacking gel issue, is that when running SDS-PAGE, I notice that the samples are surrounded by a bubble like mark, described as below

--------------- <-- unknown front
o o o o o o o o <-- samples
--------------- <-- unknown front

The samples are treated with high concentration of SDS during extraction(~3% in final concentration before adding sample buffer). Will it be the reason of the strange situation happened when running SDS-PAGE?